1. Field of the Invention
The present invention relates generally to medical devices. More particularly, it concerns a medical probe that can be used to induce localized cooling of tissue, including the brain and other tissue or organs. The localized cooling can reduce local cell death and swelling.
2. Description of Related Art
Traumatic events such as stroke, head trauma, car accidents, falls, etc. may cause localized swelling of tissues and/or organs (e.g., swelling of the brain). Swelling causes increased pressure and blood flow and decreases the ability of affected cells to dissipate heat. It is known that lowering the temperature of the affected cells not only alleviates swelling, but also helps to dissipate heat.
Most conventional cooling systems aimed at treating trauma cool globally instead of locally. In response to trauma, a patient may be subjected to an ice bath or slurry. Although effective to a degree, this type of cooling may lead to other serious problems. For instance, global cooling may cause a heart attack or organ failure.
The ability to apply localized cooling reduces or eliminates such problems. U.S. Pat. No. 6,126,684 to Gobin et al. (“the '684 patent), which is incorporated by reference, describes certain techniques to achieve relatively-localized cooling (or heating). The '684 patent describes a catheter that can be positioned to produce hypothermia in a relatively-selective area of the body without cooling the entire body system. By positioning a heat exchange catheter in a body conduit (e.g. an artery), heat can be added to or removed from the body fluid (e.g. blood) to heat or cool a selected body portion (e.g. the brain). The heat exchange catheter includes a shaft, fluid inlet and outlet lumens, and at least one balloon provided in a heat exchange region. The balloon wall provides a barrier between the body fluid (e.g. blood) and a heat exchange fluid. Although exhibiting some utility, the '684 nevertheless suffers from drawbacks. In particular, the degree of localization afforded is not easily controlled. Because the primary cooling mechanism of the '684 patent involves the cooling of, for instance, a supply fluid, it is difficult or impossible to precisely control or truly localize the cooling. Rather, an entire region (e.g. the entire brain) may be significantly cooled. Additionally, the '684 patent does not provide means to effectively monitor the localization of the cooling or quantify the amount of cooling being effected in tissue. Still further, and importantly, if a body fluid is not present, it appears that techniques of the '684 patent may be inapplicable.
U.S. Pat. No. 6,533,804 to Dobak et al. (“the '804 patent), which is incorporated by reference, describes certain techniques for selective organ heating and cooling. Similar in some respects to the '684 patent, the '804 patent describes a catheter that can be used to change the temperature of a fluid, such as blood, by heat transfer. A catheter system has an inlet lumen and an outlet lumen structured and arranged to carry a working fluid having a temperature different from the adjacent blood. Heat exchange between the two fluids may be utilized, in one embodiment, to cool blood. The '804 patent suffers from drawbacks identical or similar to those of the '684 patent.
Referenced shortcomings of conventional methodologies mentioned above are not intended to be exhaustive, but rather are among many that tend to impair the effectiveness of previously known techniques concerning localized cooling for medical applications. Other noteworthy problems may also exist; however, those mentioned here are sufficient to demonstrate that methodology appearing in the art have not been altogether satisfactory and that a significant need exists for the techniques described and claimed in this disclosure. In particular, a significant need exists for technology that would allow users to achieve localized cooling, which may greatly benefit the treatment of patients, and particularly patients exhibiting localized brain swelling.